Electronic device

ABSTRACT

Provided is an electronic device including a ramp signal generation circuit configured to generate a ramp signal having a second slope that is greater by a first level than a first slope which corresponds to an analog gain, and a slope correction circuit configured to correct the second slope of the ramp signal by the first level to obtain the first slope.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of Korean Patent Application No.10-2016-0145085, filed on Nov. 2, 2016, which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

Exemplary embodiments relate to a semiconductor design technology, andmore particularly, to an electronic device.

2. Description of the Related Art

An electronic device may include an analog-to-digital converter (ADC)for converting an analog signal to a digital signal.

For example, an image sensing device may include an ADC for convertingan analog pixel signal to a digital signal. The ADC may compare theanalog pixel signal with a ramp signal and generate the digital signalbased on the result of the comparison. The ramp signal is a comparisonsignal for determining the voltage level of the pixel signal and itsvoltage level per unit time is adjusted to be constant in a prescribedrange.

The image sensing device may adjust an analog gain by adjusting a slopeof the ramp signal. The analog gain is a parameter related to peripheralillumination conditions.

An image sensing device captures images using photosensitive propertiesof semiconductors. The image sensing device is typically classified intoa charge-coupled device (CCD) image sensor or a complementarymetal-oxide semiconductor (CMOS) image sensor. A CMOS image sensorallows for both analog and digital control circuits to be directlyimplemented on a single integrated circuit (IC), making the CMOS imagesensor the most widely used type of image sensor.

SUMMARY

Various embodiments are directed to an electronic device capable ofsubstantially maintaining the linearity of an analog gain to be constantwhen a slope of a ramp signal is adjusted according to the analog gain.

In an accordance with an embodiment, an electronic device may include: aramp signal generation circuit configured to generate a ramp signalhaving a second slope that is greater by a first level than a firstslope which corresponds to an analog gain; and a slope correctioncircuit configured to correct the second slope of the ramp signal by thefirst level to obtain the first slope.

The slope correction circuit optionally may correct the slope of theramp signal by a second level.

The ramp signal generation circuit may adjust the slope of the rampsignal on a basis of a variable resistance.

The ramp signal generation circuit may adjust the slope of the rampsignal on a basis of a variable current.

The first level and the second level may be equal to each other and aredifferent from each other.

In an accordance with another embodiment, an electronic device mayinclude: a ramp signal generation block configured to generate a rampsignal on a basis of a ramp code signal; a slope adjustment blockconfigured to adjust a slope of the ramp signal such that the rampsignal has a second slope more than a first slope corresponding to ananalog gain, on a basis of a gain code signal, the second slopecorresponding to adjusting the first slope by the first level; a firstslope correction block configured to basically correct the slope of theramp signal by the first level on a basis of a first correction codesignal; and a second slope correction block configured to secondarilycorrect the slope of the ramp signal by a second level on a basis of asecond correction code signal.

The first slope correction block secondarily may increase the slope ofthe ramp signal in a range corresponding to the first level.

The first slope correction block may include at least one first resistorpart electrically coupled in parallel to an output terminal of the rampsignal, and the first resistor part selectively reflects a firstresistance value corresponding to the first level in the output terminalon the basis of the first correction code signal.

The first resistor part basically may reflect the first resistance valuein the output terminal and secondarily reflects the first resistancevalue in the output terminal optionally.

The second slope correction block may include at least one secondresistor part electrically coupled in parallel to an output terminal ofthe ramp signal, and the second resistor part reflects a secondresistance value corresponding to the second level in the outputterminal on the basis of the second correction code signal.

The second resistor part basically may reflect the second resistancevalue in the output terminal and secondarily reflects the secondresistance value in the output terminal optionally.

The slope adjustment block may include a plurality of third resistorparts electrically coupled in parallel to an output terminal of the rampsignal, and the plurality of third resistor parts reflect a thirdresistance value corresponding to the second slope in the outputterminal on the basis of the gain code signal.

The ramp signal generation block may include: a bias signal generationunit configured to generate a bias signal having a fixed voltage levelcorresponding to a reference current; and a ramp current generation unitconfigured to supply a ramp current, which is adjusted by a prescribedlevel per unit time, to an output terminal of the ramp signal on a basisof the bias signal and the ramp code signal.

In an accordance with further another embodiment, an electronic devicemay include: a ramp signal generation block configured to generate aramp signal on a basis of a ramp code signal and to adjust a slope ofthe ramp signal on a basis of a bias signal; a bias signal generationblock configured to generate the bias signal having a second voltagelevel higher than a first voltage level corresponding to an analog gain,on a basis of a gain code signal, the second voltage level correspondingto adjusting the first voltage level by the first level; a first biassignal correction block configured to basically correct the voltagelevel of the bias signal by the first level on a basis of a firstcorrection code signal; and a second bias signal correction blockconfigured to secondarily correct the voltage level of the bias signalby a second level on a basis of a second correction code signal.

The first bias signal correction block secondarily may lower the voltagelevel of the bias signal in a range corresponding to the first level.

The first bias signal correction block may include at least one firstcorrection current generation unit electrically coupled in parallel toan output terminal of the bias signal, and the first correction currentgeneration unit selectively may supply a first correction currentcorresponding to the first level to the output terminal on the basis ofthe first correction code signal.

The first correction current generation unit basically may supply thefirst correction current to the output terminal and secondarily suppliesthe first correction current to the output terminal optionally.

The second bias signal correction block may include at least one secondcorrection current generation unit electrically coupled in parallel toan output terminal of the bias signal, and the second correction currentgeneration unit supplies a second correction current corresponding tothe second level to the output terminal on the basis of the secondcorrection code signal.

The second correction current generation unit basically may supply thesecond correction current to the output terminal and secondarilysupplies the second correction current to the output terminaloptionally.

The bias signal generation block may include a plurality of bias currentgeneration units electrically coupled in parallel to an output terminalof the bias signal, and the plurality of bias current generation unitssupply a bias current corresponding to the second voltage level to theoutput terminal on the basis of the gain code signal.

The ramp signal generation block may include: a ramp current generationunit configured to supply a ramp current, which is adjusted by aprescribed unit current amount per unit time, to an output terminal ofthe ramp signal, on the basis of the ramp code signal, and to adjust theunit current amount on a basis of the bias signal; and a fixed resistorunit configured to convert the ramp current into the ramp signal.

In an accordance with further another embodiment, a method for drivingan electronic device may include: intentionally generating a ramp signalhaving a second slope increased or decreased more than a first slopecorresponding to an analog gain; basically correcting the ramp signal tohave the first slope; and secondarily correcting the ramp signal to havethe first slope when the ramp signal has a third slope increased ordecreased more than the first slope.

In accordance with the embodiments of the present embodiments, when aslope of a ramp signal corresponding to an analog gain is adjusted, itis possible to substantially maintain the linearity of the analog gainto be constant, so that it is possible to improve the operationalreliability of an electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent to those skilled in the art to which thepresent invention pertains by the following detailed description withreference to the attached drawings in which:

FIG. 1 is a block diagram illustrating an electronic device inaccordance with a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a ramp signal generation circuit and aslope correction circuit illustrated in FIG. 1.

FIG. 3 to 6 are graphs illustrating performance of an electronic deviceillustrated in FIG. 1.

FIG. 7 is a block diagram illustrating an electronic device inaccordance with a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a ramp signal generation circuit and aslope correction circuit illustrated in FIG. 7.

DETAILED DESCRIPTION

Various embodiments will be described below in more detail withreference to the accompanying drawings. The present invention may,however, be embodied in different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the present invention to those skilled inthe art. Throughout the disclosure, like reference numerals refer tolike parts throughout the various figures and embodiments of the presentinvention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventiveconcept. As used herein, singular forms are intended to include theplural forms as well, unless the context clearly indicates otherwise. Itwill be further understood that the terms “comprises,” “comprising,”“includes,” and/or “including” when used in this specification, indicatethe presence of stated features, but do not preclude the presence oraddition of one or more other features. As used herein, the term“and/or” indicates any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms “first”, “second”,“third”, and so on may be used herein to describe various elements,these elements are not limited by these terms. These terms are used todistinguish one element from another element. Thus, a first elementdescribed below could also be termed as a second or third elementwithout departing from the spirit and scope of the present invention.

It is noted that the drawings are simplified schematics and as such arenot necessarily drawn to scale. In some instances, various parts of thedrawings may have been exaggerated in order to more clearly illustratecertain features of the illustrated embodiments.

It is further noted that in the following description, specific detailsare set forth for facilitating the understanding of the presentinvention, however, the present invention may be practiced without someof these specific details. Also, it is noted, that well-known structuresand/or processes may have only been described briefly or not describedat all to avoid obscuring the present disclosure with unnecessary wellknown details.

It is also noted, that in some instances, as would be apparent to thoseskilled in the relevant art, an element (also referred to as a feature)described in connection with one embodiment may be used singly or incombination with other elements of another embodiment, unlessspecifically indicated otherwise.

FIG. 1 is a block diagram illustrating an electronic device inaccordance with a first embodiment of the present invention.

Referring to FIG. 1, the electronic device may include a ramp signalgeneration circuit 100 and a slope correction circuit 200.

The ramp signal generation circuit 100 may generate a ramp signal VRAMPon the basis of a ramp code signal RC<1:A> and a gain code signalAGC<1:B>. The ramp signal VRAMP may have a second slope that is greaterthan a first slope corresponding to an analog gain. The second slope maybe obtained by adjusting the first slope by a first level. The rampsignal generation circuit 100 may generate the ramp signal VRAMP havingthe second slope. For example, the ramp signal generation circuit 100may generate the ramp signal VRAMP having the second slope by increasingby a first level the first slope. In an embodiment, the ramp signalgeneration circuit 100 may adjust the slope of the ramp signal VRAMP toattain the second slope by employing a variable resistance.

On the basis of a correction code signal CC<1:C>, the slope correctioncircuit 200 may correct the slope of the ramp signal VRAMP by the firstlevel. The slope correction circuit 200 may also perform a secondcorrection of the slope of the ramp signal VRAMP by a second level. Thesecond correction may be optional. In some embodiments, the first leveland the second level may be substantially equal to each other.Alternatively, the first level and the second level may be differentfrom each other.

FIG. 2 illustrates a diagram illustrating an exemplary configuration ofthe ramp signal generation circuit 100 and the slope correction circuit200 illustrated in FIG. 1.

Referring to FIG. 2, the ramp signal generation circuit 100 may includea ramp signal generation block 110 and a slope adjustment block 120.

The ramp signal generation block 110 may generate the ramp signal VRAMPwhich is ramped in a prescribed range, on the basis of the ramp codesignal RC<1:A>. For example, the ramp signal generation block 110 mayinclude a bias signal generation unit 111 and a ramp current generationunit 113.

The bias signal generation unit 111 may generate a bias signal BS havinga predetermined voltage level corresponding to a reference current IREF.

The ramp current generation unit 113 may supply a ramp current, which isadjusted by a prescribed level per unit time, to an output terminal ofthe ramp signal VRAMP on the basis of the bias signal BS and the rampcode signal RC<1:A>. For example, the ramp current generation unit 113may include first to A^(th) current mirrors electrically coupled inparallel to one another between a power supply voltage terminal and theoutput terminal (where “A” is a natural number equal to or more than 2).The first to A^(th) current mirrors may be sequentially selected on thebasis of first to A^(th) ramp control signals included in the ramp codesignal RC<1:A>, and may generate a mirroring current corresponding tothe reference current IREF as a ramp current on the basis of the biassignal BS.

The slope adjustment block 120 may adjust the slope of the ramp signalVRAMP on the basis of the gain code signal AGC<1:B>. Particularly, theslope adjustment block 120 may adjust the slope of the ramp signal VRAMPsuch that the ramp signal VRAMP has the second slope which is greater bythe first level than the first slope. For example, the slope adjustmentblock 120 may include first to B^(th) slope adjustment resistor partselectrically coupled in parallel to one another between the outputterminal and a ground voltage terminal (where “B” is a natural numberequal to or more than 2). At least one of the first to B^(th) slopeadjustment resistor parts may be selected on the basis of first toB^(th) gain control signals included in the gain code signal AGC<1:B>driving corresponding switches, and the first to B^(th) slope adjustmentresistor parts may reflect a first resistance value corresponding to thesecond slope in the output terminal. The resistors included in the firstto B^(th) slope adjustment resistor parts may have resistance valuessubstantially equal to one another or different from one another.

The slope correction circuit 200 may include a first slope correctionblock 210 and a second slope correction block 220.

On the basis of at least one (hereinafter, referred to as a “firstcorrection code signal CC<1:D>”) of first and C^(th) correction controlsignals included in the correction code signal CC<1:C>, the first slopecorrection block 210 may basically increase the slope of the ramp signalVRAMP by the first level (where “C” is a natural number equal to or morethan 2 and “D” is a natural number equal to or more than 1), and maysecondarily decrease the slope of the ramp signal VRAMP in a rangecorresponding to the first level. For example, the first slopecorrection block 210 may include first to D^(th) slope correctionresistor parts electrically coupled in parallel to one another betweenthe output terminal and the ground voltage terminal. The first to D^(th)slope correction resistor parts may selectively reflect a secondresistance value corresponding to the first level in the output terminalon the basis of the first correction code signal CC<1:D>. For example,the first to D^(th) slope correction resistor parts may primarilyreflect the second resistance value in the output terminal and maysecondarily reflect the second resistance value in the output terminaloptionally.

On the basis of the remaining signal (hereinafter, referred to as a“second correction code signal CC<D+1:C>”) of the first and C^(th)correction control signals included in the correction code signalCC<1:C>, the second slope correction block 220 may secondarily decreasethe slope of the ramp signal VRAMP by the second level. For example, thesecond slope correction block 220 may include (D+1)^(th) to C^(th) slopecorrection resistor parts electrically coupled in parallel to the outputterminal. The (D+1)^(th) to C^(th) slope correction resistor parts mayreflect a third resistance value corresponding to the second level inthe output terminal on the basis of the second correction code signalCC<D+1:C>. For example, the (D+1)^(th) to C^(th) slope correctionresistor parts may primarily reflect the third resistance value in theoutput terminal and may secondarily reflect the third resistance valuein the output terminal optionally.

Hereinafter, an operation of the electronic device having the aboveconfiguration in accordance with the first embodiment will be described.

The following configuration of the first embodiment will be described asan example. For example, the slope adjustment block 120 may includefirst to fourth slope adjustment resistor parts, the first slopecorrection block 210 may include a first slope correction resistor part,and the second slope correction 220 may include second to sixth slopecorrection resistor parts. In such a case, the first to fourth slopeadjustment resistor parts may be respectively controlled by first tofourth gain control signals AGC<1:4> included in a gain code signalAGC<1:4>, the first slope correction resistor part may be controlled bya first correction control signal CC<1>, and the second to sixth slopecorrection resistor parts may be respectively controlled by second tosixth correction control signals CC<2:6>.

An operation in the case of requiring no correction will be described.For example, the case of requiring no correction may include a case inwhich the first to fourth slope adjustment resistor parts have beenideally designed without any process variation.

The ramp signal generation circuit 100 may generate the ramp signalVRAMP on the basis of the ramp code signal RC<1:A>. For example, on thebasis of the gain code signal AGC<1:4>, the ramp signal generationcircuit 100 may intentionally generate the ramp signal VRAMP having thesecond slope decreased by the first level more than the first slopecorresponding to the analog gain.

The slope correction circuit 200 may primarily correct the slope of theramp signal VRAMP such that the ramp signal VRAMP has the first slopeincreased by the first level more than the second slope. For example,the first slope correction resistor part (or a first correction means)included in the slope correction circuit 200 is activated (or enabled)on the basis of the first correction code signal CC<1>, so that theslope of the ramp signal VRAMP may increase. In this case, the second tosixth correction code signals CC<2:6> may be inactivated (or disabled).

For example, in the case of requiring no correction, control signalsaccording to the analog gain may be generated as indicated in Table 1below.

TABLE 1 Analog AGC AGC AGC AGC CC CC CC CC CC CC Gain <1> <2> <3> <4><1> <2> <3> <4> <5> <6> 1 1 0 0 0 1 0 0 0 0 0 2 1 1 0 0 1 0 0 0 0 0 4 11 1 0 1 0 0 0 0 0 8 1 1 1 1 1 0 0 0 0 0

In Table 1 above, “1” may represent that a corresponding control signalis activated and “0” may represent that a corresponding control signalis inactivated.

Next, the case of requiring correction will be described. For example,the case of requiring correction may include a case in which the firstto fourth slope adjustment resistor parts have been non-Ideally designeddue to a process variation. Hereinafter, two examples will be described.

In the first example, the case in which a resistance value of the firstslope adjustment resistor part has decreased due to a process variationwill be described.

The ramp signal generation circuit 100 may generate the ramp signalVRAMP on the basis of the ramp code signal RC<1:A>. In this case, theramp signal generation circuit 100 should intentionally generate theramp signal VRAMP having the second slope instead of the first slope onthe basis of the gain code signal AGC<1:4>, but the ramp signalgeneration circuit 100 may generate the ramp signal VRAMP having a thirdslope due to a process variation. The third slope may be less than thesecond slope.

The slope correction circuit 200 may perform a first increase of theslope of the ramp signal VRAMP by the first level on the basis of thefirst correction code signal CC<1>. For example, the first slopecorrection resistor part is enabled on the basis of the first correctioncode signal CC<1>, so that the slope of the ramp signal VRAMP mayincrease. However, since the slope of the ramp signal VRAMP hasdecreased due to a process variation, the slope correction circuit 200needs to be further adjusted by performing a second increase of theslope of the ramp signal VRAMP on the basis of the first correction codesignal CC<1> and the second to sixth correction code signals CC<2:6>.For example, the first slope correction resistor part is disabled on thebasis of the first correction code signal CC<1>, so that the ramp signalVRAMP may be corrected to have the first slope.

For example, in the case of requiring correction, control signalsaccording to the analog gain may be generated as indicated in Table 2below.

TABLE 2 Analog AGC AGC AGC AGC CC CC CC CC CC CC Gain <1> <2> <3> <4><1> <2> <3> <4> <5> <6> 1 1 0 0 0 0 0 0 0 0 0 2 1 1 0 0 0 0 0 0 0 0 4 11 1 0 0 0 0 0 0 0 8 1 1 1 1 0 0 0 0 0 0

In Table 2 above, it can be understood that the first gain code signalAGC<1> activates all analog gains. In such a case, sinceparallel-coupled resistors (e.g., the first to fourth slope adjustmentresistor parts) gradually increase with an increase in the analog gain,the influence of a resistance value reflected by the first slopeadjustment resistor part may be gradually reduced. As a consequence, thedegree of a decrease in the third slope may be gradually reduced with anincrease in the analog gain.

In Table 2 above, the second to sixth correction code signals CC<2:6>are all inactivated, however, is not limited to such an example only.

FIGS. 3 and 4 are graphs illustrating improved performance of theelectronic device in accordance with the first embodiment of the presentinvention.

FIG. 3 illustrates a graph showing an actual analog gain (AG) withrespect to an ideal analog gain (AG), and FIG. 4 illustrates a graphshowing the linearity of an analog gain (AG linearity) with respect tothe ideal analog gain (AG).

When the resistance value of the first slope adjustment resistor parthas decreased due to any process variation, the slope of the ramp signalVRAMP may decreased, so that the actual analog gain (AG) may be lowerthan the ideal analog gain (AG) as illustrated in FIG. 3 ({circle around(a)}). As described above, since the degree of a decrease in the thirdslope may be gradually reduced with an increase in the ideal analog gain(AG), the actual analog gain (AG) may decrease as compared with theideal analog gain (AG).

Accordingly, when the resistance value of the first slope adjustmentresistor part has unexpectedly decreased, the first slope adjustmentresistor part is allowed to be disabled, so that the slope of the rampsignal VRAMP may be increased and thus the actual analog gain (AG) maybe upward to an approximate value of the ideal analog gain (AG) ({circlearound (b)}). The actual analog gain (AG) may be defined by Equation 1below.

actual AG=(R _(AG=1) /R _(AG=k))={S _(AG=1) /S _(AG=k)}  Equation 1

In Equation 1 above, “R_(AG=k)” denotes a resistance value reflected inthe output terminal of the ramp signal VRAMP when the actual analog gain(AG) is ‘k’ (where k is 1, 2, 4, or 8), “R_(AG=1)” denotes a resistancevalue reflected in the output terminal of the ramp signal VRAMP when theactual analog gain (AG) is ‘1’, “S_(AG=k)” denotes the slope of the rampsignal VRAMP when the actual analog gain (AG) is ‘k’ (where k is 1, 2,4, or 8), and “S_(AG=1)” denotes the slope of the ramp signal VRAMP whenthe actual analog gain (AG) is ‘1’.

When the actual analog gain (AG) is lower than the ideal analog gain(AG) ({circle around (a)}), the linearity of an analog gain (AGlinearity) with respect to the ideal analog gain (AG) may be downward asillustrated in FIG. 4 ({circle around (c)}). Furthermore, the actualanalog gain (AG) is upward to the approximate value of the ideal analoggain (AG) ({circle around (b)}), so that the linearity of the analoggain (AG linearity) with respect to the ideal analog gain (AG) may beupward to a normal value ({circle around (d)}). The linearity of theanalog gain (AG linearity) may be defined by Equation 2 below.

AG linearity={actual AG _(A=k)/actual AG _(AG=1)}  Equation 2

In the second example, the case in which the resistance value of thefirst slope adjustment resistor part has increased due to any processvariation will be described.

The ramp signal generation circuit 100 may generate the ramp signalVRAMP on the basis of the ramp code signal RC<1:A>. In this case, theramp signal generation circuit 100 should intentionally generate theramp signal VRAMP having the second slope instead of the first slope onthe basis of the gain code signal AGC<1:4>, but the ramp signalgeneration circuit 100 may generate the ramp signal VRAMP having a thirdslope due to any process variation. The third slope may be more than thesecond slope.

The slope correction circuit 200 may primarily increase the slope of theramp signal VRAMP on the basis of the first correction code signalCC<1>, and may secondarily increase the slope of the ramp signal VRAMPon the basis of the second to sixth correction code signals CC<2:6>. Forexample, the first slope correction resistor part is enabled on thebasis of the first correction code signal CC<1> and at least one of thesecond to sixth slope correction resistor parts (or a second correctionmeans) is enabled on the basis of the second to sixth correction codesignals CC<2:6>, so that the ramp signal VRAMP may be corrected to havethe first slope.

For example, in the case of requiring the aforementioned correction,control signals according to the analog gain may be generated asindicated in Table 3 below.

TABLE 3 Analog AGC AGC AGC AGC CC CC CC CC CC CC Gain <1> <2> <3> <4><1> <2> <3> <4> <5> <6> 1 1 0 0 0 1 1 0 0 0 0 2 1 1 0 0 1 1 0 0 0 0 4 11 1 0 1 1 0 0 0 0 8 1 1 1 1 1 1 0 0 0 0

In Table 3 above, it can be understood that the first gain code signalAGC<1> activates all analog gains. In such a case, sinceparallel-coupled resistors (e.g., the first to fourth slope adjustmentresistor parts) gradually increase with an increase in the analog gain,the influence of a resistance value reflected by the first slopeadjustment resistor part may be gradually reduced. As a consequence, thedegree of an increase in the third slope may be gradually reduced withan increase in the analog gain.

In Table 3 above, only some of the second to sixth correction codesignals CC<2:6> are activated as an example, however, it is noted thatthe invention is not limited in this way.

FIG. 5 and FIG. 6 illustrate graphs illustrating improved performance ofthe electronic device in accordance with the first embodiment of thepresent invention.

FIG. 5 illustrates a graph showing the actual analog gain (AG) withrespect to the ideal analog gain (AG), and FIG. 6 illustrates a graphshowing the linearity of an analog gain (AG linearity) with respect tothe ideal analog gain (AG).

When the resistance value of the first slope adjustment resistor parthas increased due to any process variation, the slope of the ramp signalVRAMP may increase, so that the actual analog gain (AG) may be upperthan the ideal analog gain (AG) as illustrated in FIG. 5 ({circle around(a)}). As described above, since the degree of an increase in the thirdslope may be gradually reduced with an increase in the ideal analog gain(AG), the actual analog gain (AG) may increase as compared with theideal analog gain (AG).

Accordingly, when the resistance value of the first slope adjustmentresistor part has unexpectedly increased, at least one of the second tosixth slope correction resistor parts is allowed to be enabled, so thatthe slope of the ramp signal VRAMP may be decreased and thus the actualanalog gain (AG) may be downward to the approximate value of the idealanalog gain (AG) ({circle around (b)}).

When the actual analog gain (AG) is upper than the ideal analog gain(AG) ({circle around (a)}), the linearity of the analog gain (AGlinearity) with respect to the ideal analog gain (AG) may be upward asillustrated in FIG. 6 ({circle around (c)}). Furthermore, the actualanalog gain (AG) is downward to the approximate value of the idealanalog gain (AG) ({circle around (b)}), so that the linearity of theanalog gain (AG linearity) with respect to the ideal analog gain (AG)may be downward to a normal value ({circle around (d)}).

FIG. 7 is a block diagram illustrating an electronic device inaccordance with a second embodiment of the present invention.

Referring to FIG. 7, the electronic device may include a ramp signalgeneration circuit 300 and a slope correction circuit 400.

The ramp signal generation circuit 300 may generate a ramp signal VRAMPon the basis of a ramp code signal RC<1:A> and a gain code signalAGC<1:B>. The ramp signal VRAMP may have a second slope more than afirst slope corresponding to an analog gain, and the second slopecorresponds to the result of adjusting the first slope by a first level.The ramp signal generation circuit 300 may generate the ramp signalVRAMP having the second slope instead of the first slope. For example,the ramp signal generation circuit 300 may generate the ramp signalVRAMP having the second slope decreased by the first level more than thefirst slope. The ramp signal generation circuit 300 may adjust the slopeof the ramp signal VRAMP on the basis of a variable current.

On the basis of a correction code signal CC<1:C>, the slope correctioncircuit 400 may primarily correct the slope of the ramp signal VRAMP bythe first level and secondarily correct the slope of the ramp signalVRAMP by a second level. The second correction may be optional. In someembodiments, the first level and the second level may be substantiallyequal to each other. Alternatively, the first level and the second levelmay be different from each other. The slope correction circuit 400 mayindirectly correct the slope of the ramp signal VRAMP through the rampsignal generation circuit 300.

FIG. 8 illustrates a diagram illustrating an exemplary configuration ofthe ramp signal generation circuit 300 and the slope correction circuit400 illustrated in FIG. 7.

Referring to FIG. 8, the ramp signal generation circuit 300 may includea ramp signal generation block 310 and a bias signal generation block320.

The ramp signal generation block 310 may generate the ramp signal VRAMPwhich is ramped in a prescribed range, on the basis of the ramp codesignal RC<1:A>, and may adjust the slope of the ramp signal VRAMP on thebasis of a bias signal BS. For example, the ramp signal generation block310 may include a ramp current generation unit 311 and a fixed resistorunit 313.

The ramp current generation unit 311 may supply a ramp current, which isadjusted by a prescribed unit current amount per unit time, to an outputterminal of the ramp signal VRAMP, on the basis of the ramp code signalRC<1:A>, and may adjust the unit current amount on the basis of the biassignal BS. For example, the ramp current generation unit 311 may includea plurality of unit current generation sections electrically coupledbetween a power supply voltage terminal and the output terminal. Theplurality of unit current generation sections may adjust the unitcurrent amount on the basis of the bias signal BS, and may sequentiallysupply a unit current to the output terminal on the basis of first toA^(th) ramp control signals included in the ramp code signal RC<1:A>.

The fixed resistor unit 313 may convert the ramp current into the rampsignal VRAMP. For example, the fixed resistor unit 313 may beelectrically coupled between the output terminal and a ground voltageterminal, and may have a fixed resistance value.

The bias signal generation block 320 may generate the bias signal BShaving a second voltage level higher than a first voltage level by afirst level corresponding to an analog gain, on the basis of a gain codesignal AGC<1:B>. For example, the bias signal generation block 320 mayinclude a plurality of bias current generation units 321 which may beselected by corresponding switches which are driven by the gain codesignal AGC<1:B>, and a current source 323.

The plurality of bias current generation units 321 may be electricallycoupled in parallel to one another between the power supply voltageterminal and an output terminal of the bias signal BS. At least one ofthe plurality of bias current generation units 321 may be selected onthe basis of first to B^(th) gain control signals included in the gaincode signal AGC<1:B>. The plurality of bias current generation units 321may supply a bias current corresponding to the second voltage level tothe output terminal of the bias signal BS.

The current source 323 may be electrically coupled between the outputterminal of the bias signal BS and the ground voltage terminal. Thecurrent source 323 may generate a reference current IREF.

The slope correction circuit 400 may include a first bias signalcorrection block 410 and a second bias signal correction block 420.

The first bias signal correction block 410 may primarily lower a voltagelevel of the bias signal BS by the first level and may secondarilyincrease the voltage level of the bias signal BS in a rangecorresponding to the first level, on the basis of at least one(hereinafter, referred to as a “first correction code signal CC<1:D>” offirst to C^(th) correction control signals included in the correctioncode signal CC<1:C>. For example, the first bias signal correction block410 may include at least one first correction current generation unitelectrically coupled in parallel to one another between the power supplyvoltage terminal and the output terminal of the bias signal BS. Thefirst correction current generation unit may selectively supply a firstcorrection current corresponding to the first level to the outputterminal of the bias signal BS on the basis of the first correction codesignal CC<1:D>. For example, the first correction current generationunit may primarily supply the first correction current to the outputterminal of the bias signal BS, and may secondarily supply the firstcorrection current to the output terminal of the bias signal BSoptionally.

The second bias signal correction block 420 may secondarily lower thevoltage level of the bias signal BS by the second level on the basis ofthe remaining signal (hereinafter, referred to as a “second correctioncode signal CC<D+1:C>” of the first to C^(th) correction control signalsincluded in the correction code signal CC<1:C>. For example, the secondbias signal correction block 420 may include at least one secondcorrection current generation unit electrically coupled in parallel toone another between the power supply voltage terminal and the outputterminal of the bias signal BS. The second correction current generationunit may selectively supply a second correction current corresponding tothe second level to the output terminal of the bias signal BS on thebasis of the second correction code signal CC<D+1:C>. For example, thesecond correction current generation unit may primarily supply thesecond correction current to the output terminal of the bias signal BS,and may secondarily supply the second correction current to the outputterminal of the bias signal BS optionally.

Hereinafter, since the operation of the electronic device having theaforementioned configuration in accordance with the second embodimentcan be derived or modified through the operation of the electronicdevice in accordance with the first embodiment, a description thereof isomitted.

In accordance with the embodiments as described above, it is possible tocorrect the non-linearity of an analog gain occurring due to the processvariation of a circuit directly or indirectly participating ingenerating a ramp signal.

Although various embodiments have been described for illustrativepurposes, it will be apparent to those skilled in the art that variouschanges and modifications may be made without departing from the spiritand scope of the invention as defined in the following claims.

What is claimed is:
 1. An electronic device comprising: a ramp signalgeneration circuit configured to generate a ramp signal having a secondslope that is greater by a first level than a first slope whichcorresponds to an analog gain; and a slope correction circuit configuredto correct the second slope of the ramp signal by the first level toobtain the first slope.
 2. The electronic device of claim 1, wherein theslope correction circuit optionally correct the slope of the ramp signalby a second level.
 3. The electronic device of claim 1, wherein the rampsignal generation circuit adjusts the slope of the ramp signal on abasis of a variable resistance.
 4. The electronic device of claim 1,wherein the ramp signal generation circuit adjusts the slope of the rampsignal on a basis of a variable current.
 5. An electronic devicecomprising: a ramp signal generation block configured to generate a rampsignal on a basis of a ramp code signal; a slope adjustment blockconfigured to adjust a slope of the ramp signal such that the rampsignal has a second slope more than a first slope corresponding to ananalog gain, on a basis of a gain code signal, the second slopecorresponding to adjusting the first slope by the first level; a firstslope correction block configured to basically correct the slope of theramp signal by the first level on a basis of a first correction codesignal; and a second slope correction block configured to secondarilycorrect the slope of the ramp signal by a second level on a basis of asecond correction code signal.
 6. The electronic device of claim 5,wherein the first slope correction block secondarily increase the slopeof the ramp signal in a range corresponding to the first level.
 7. Theelectronic device of claim 5, wherein the first slope correction blockincludes at least one first resistor part electrically coupled inparallel to an output terminal of the ramp signal, and the firstresistor part selectively reflects a first resistance valuecorresponding to the first level in the output terminal on the basis ofthe first correction code signal.
 8. The electronic device of claim 7,wherein the first resistor part basically reflects the first resistancevalue in the output terminal and secondarily reflects the firstresistance value in the output terminal optionally.
 9. The electronicdevice of claim 5, wherein the second slope correction block includes atleast one second resistor part electrically coupled in parallel to anoutput terminal of the ramp signal, and the second resistor partreflects a second resistance value corresponding to the second level inthe output terminal on the basis of the second correction code signal.10. The electronic device of claim 9, wherein the second resistor partbasically reflects the second resistance value in the output terminaland secondarily reflects the second resistance value in the outputterminal optionally.
 11. The electronic device of claim 5, wherein theslope adjustment block includes a plurality of third resistor partselectrically coupled in parallel to an output terminal of the rampsignal, and the plurality of third resistor parts reflect a thirdresistance value corresponding to the second slope in the outputterminal on the basis of the gain code signal.
 12. The electronic deviceof claim 5, wherein the ramp signal generation block comprises: a biassignal generation unit configured to generate a bias signal having afixed voltage level corresponding to a reference current; and a rampcurrent generation unit configured to supply a ramp current, which isadjusted by a prescribed level per unit time, to an output terminal ofthe ramp signal on a basis of the bias signal and the ramp code signal.13. An electronic device comprising: a ramp signal generation blockconfigured to generate a ramp signal on a basis of a ramp code signaland to adjust a slope of the ramp signal on a basis of a bias signal; abias signal generation block configured to generate the bias signalhaving a second voltage level higher than a first voltage levelcorresponding to an analog gain, on a basis of a gain code signal, thesecond voltage level corresponding to adjusting the first voltage levelby the first level; a first bias signal correction block configured tobasically correct the voltage level of the bias signal by the firstlevel on a basis of a first correction code signal; and a second biassignal correction block configured to secondarily correct the voltagelevel of the bias signal by a second level on a basis of a secondcorrection code signal.
 14. The electronic device of claim 13, whereinthe first bias signal correction block secondarily lowers the voltagelevel of the bias signal in a range corresponding to the first level.15. The electronic device of claim 13, wherein the first bias signalcorrection block includes at least one first correction currentgeneration unit electrically coupled in parallel to an output terminalof the bias signal, and the first correction current generation unitselectively supplies a first correction current corresponding to thefirst level to the output terminal on the basis of the first correctioncode signal.
 16. The electronic device of claim 15, wherein the firstcorrection current generation unit basically supplies the firstcorrection current to the output terminal and secondarily supplies thefirst correction current to the output terminal optionally.
 17. Theelectronic device of claim 13, wherein the second bias signal correctionblock includes at least one second correction current generation unitelectrically coupled in parallel to an output terminal of the biassignal, and the second correction current generation unit supplies asecond correction current corresponding to the second level to theoutput terminal on the basis of the second correction code signal. 18.The electronic device of claim 17, wherein the second correction currentgeneration unit basically supplies the second correction current to theoutput terminal and secondarily supplies the second correction currentto the output terminal optionally.
 19. The electronic device of claim13, wherein the bias signal generation block includes a plurality ofbias current generation units electrically coupled in parallel to anoutput terminal of the bias signal, and the plurality of bias currentgeneration units supply a bias current corresponding to the secondvoltage level to the output terminal on the basis of the gain codesignal.
 20. The electronic device of claim 13, wherein the ramp signalgeneration block comprises: a ramp current generation unit configured tosupply a ramp current, which is adjusted by a prescribed unit currentamount per unit time, to an output terminal of the ramp signal, on thebasis of the ramp code signal, and to adjust the unit current amount ona basis of the bias signal; and a fixed resistor unit configured toconvert the ramp current into the ramp signal.